Closed loop and narrowband sensors
 

on my v3 WRX JDM I have 2 lambda sensors,one in the DP just after the turbo and a smaller one at the bottom of the DP. Do both sensors have an affect on the closed loop fueling? I am getting some strange readings,on idle the lambdaV is jumping from 0.1-0.8v and the STFT(corse fuel correction on ESL) Is pretty steady at -4% to -8% which doesn't seem too bad although seems I'm a little rich on idle.
It's when I drive with 10%throttle and 3000RPM the lambdaV jumps around from 0.04v to 0.8v And the STFT goes mad jumping between -6 to +10 which I'm guessing might indicate a problem? I will have a check for vac leaks ect. When I went catless I left out the rear lambda and just have this tied up,would this have an affect on the closed loop,or is the ECU only using the front one ?

Cheers
Rich

i cant help with your lambda readings but the second smaller sensor you talk about is the cat temp sensor, so can either be left as you have tied up out of the way or disconnected.

Nice one,thanks at least I can rule that out as a possible problem.

i've not seen the insides of the classic ECU's, but on the newage cars the rear o2 is used to determine if the cat is working as expected or if a fault code should be flagged. That's why its only a narrowband sensor. Some of the newer cars the ecu will forcable change the closed loop target and the monitor the rear o2 to makes sure the cat is working so tieing it into free air causes closed loop fuelling issues.

On the bugs (and so I would assume on the earlier cars) the rear o2 can be coded out and it has no effect on the closed loop targets. The a/f corrections on a stock car are usually +/-1 but it's normal to see some movement as there is a minimum and maximum closed loop target it's not a fixed value.

-4 to -8 would mean the ecu is removing fuel, maybe your maf scale is too high or your injectors are bigger than the ECU thinks they are. Either way the ECU is expecting more air than actually turns up so uses the o2 reading to remove some fuel.

Similar volts to my v3
But my coarse fuel always at 0
Have u looked at ur fuel trims

My LTFT's look ok but I reset the ECU so not to sure how long it takes to learn? Right now the LTFT looks good with 1.0 in every cell apart from one has 0.99 and another 1.01.
I might be possible that I have the wrong base map for my car so the injector scale and Maf calibrations are out?

What model v3 have you got Jaysz? And what are your stock injector size and Maf ? I'm running 440's and Orange Maf

Those trims ok
I have v3 sti ra 440's but increased pressure and maffless
I have standard map for v3 sti which has orange maff so scaling probably same
Ur not going get afr wideband same as target unless car is standard

Cheers Jay,yours will be a 6s ECU then I guess? Mine is the 1s and is a non STI RA,I'm not 100% sure what injectors and Maf are on the v3 WRX? But I would guess they must be the same as it uses the same ECU as mine.

Yeah 6s that shows maff scale of 22137 for orange maff
Not sure about ur car but doubt if esl sent u a ra map unless same

The lambda in correct operation is suppose to cycle, what you're seeing is exactly what you're supposed to see.

22137 is what I have which means I have the correct scale for my Maf,cheers.


Thanks Martyn,good to know this is working as it should,now I just need to confirm I have the correct Injector scale for the base rom and my standard 440cc injectors.

where are you guys getting the scales from for various MAF`s ? (orange/green etc)

I run a green MAF and in my ESL Map i have a MAF sensor scale of 22978 just wondering if thats correct now ha

The scale I put up is from orange maff from a standard 6s map
If maffless then need to adjust maff scale to get load close to what would be using maff at high load

Ah rite so your just putting up what was in the MAP when you receieved the ESL board ?, you dont have a list of the scales to corespond to each colour MAF ?

ok cheers

Not sure as first map I didn't do as was installed when board was being developed but the scaling is of a standard subaru map
Only have 6s maf and maffless